The present invention relates to an electronic information processing method and system for embedding various accessory or additional information, such as information indicative of copyright, name, composer, date of completion and lyrics of a music piece, information indicative of machine model name, news text information and text data like ID data, etc. as electronic watermark information in main information such as performance data, picture information or waveform data, and/or retrieving or taking out additional information embedded as electronic watermark information in main information, as well as a computer-readable storage medium containing programs for implementing the electronic information processing method.
As typically shown in Japanese Patent Laid-open Publication No. HEI-11-39796 (corresponding to U.K. Patent Application Laid-open Publication No. 2,314,949 A), it has been known to embed accessory or additional information, indicative of a name, composer, etc. of a music piece, etc., at respective lowermost bits of individual velocity data included in performance data constituting main information, and then retrieve the embedded additional information from among the performance data. Similar technique is disclosed in U.K. Patent Application Laid-open Publication No. 2,330,498 A).
However, because the conventionally-known techniques embed the additional information in relatively simple form, there has been the serious problem that the embedding schemes are readily read or seen through by an unauthorized dishonest user and thus the embedded additional information is intentionally (or maliciously) altered by the unauthorized dishonest user. Further, because the velocity data are among those data that can be altered relatively easily, there has been the possibility that the additional information embedded in the velocity data is altered unintentionally or unconsciously by an authorized user as the user alters the velocity data, for example, during editing of the performance data.
In view of the foregoing, it is an object of the present invention to provide a unique electronic information processing method and system and storage medium where a novel or improved scheme is employed for embedding additional information in main information without the problems encountered by the prior art.
It is another object of the present invention to provide an electronic information processing method and system and storage medium which can effectively prevent additional information from being read or seen through and hence intentionally or maliciously altered by any unauthorized dishonest user.
It is still another object of the present invention to provide an electronic information processing method and system and storage medium which can effectively prevent additional information from being altered unintentionally or unconsciously by an authorized user.
According to a first aspect of the present invention, there is provided a method of embedding additional information, as an electronic watermark, in main information including a plurality of data, which method is characterized by comprising a step of changing arrangement (placement) or order of the data in the main information in accordance with a value of the additional information to be embedded and also with a predetermined encoding algorithm. With this inventive method, the electronic watermark of the additional information is embedded in the form of a change in the arrangement or order of the data, without values of the data in the main information themselves being changed.
The present also provides an improved method of decoding additional information from main information having an electronic watermark embedded therein in accordance with the aforementioned first aspect, which is characterized by comprising: a step of acquiring decoding key information corresponding to the encoding algorithm; and a step of inversely executing the encoding algorithm on the basis of the decoding key information acquired by the step of acquiring, to thereby decode the additional information hidden in the arrangement or order of the data in the main information.
According to the above-mentioned first aspect of the present invention, the electronic watermark corresponding to the additional information is embedded in the form of a change in the arrangement or order of the data without values of the data in the main information themselves being changed at all. With no change in the data values of the main information, the main information can be reproduced quite reliably. In one embodiment, the main information comprises music performance data associated with a plurality of channels, and the change in the arrangement or order of the data in the main information is made by changing the channels of the music performance data, i.e., by changing the correspondency between the channels and the music performance data. Even in the case where the original channel assignment or arrangement in the main information has been changed, reproduction of a music performance based on the performance data can be carried out with no problem because tones to be generated themselves have not been changed at all by the channel rearrangement. However, because particular information hidden in the channel arrangement can not be known unless appropriate key information is obtained, this inventive feature can be very helpful in preventing an unauthorized dishonest user from tampering with or altering the information. Further, since the channel rearrangement in the music performance data generally does not take place very often in ordinary editing of the performance data, it is very unlikely that the additional information is altered unintentionally or unconsciously. The present invention is not limited to the above-mentioned channel rearrangement; for example, the arrangement or order of the data may be changed with respect to a particular factor a change of which does not substantially adversely influence music reproduction based on the music performance data.
According to a second aspect of the present invention, there is provided a method of embedding additional information, as an electronic watermark, in main information including a plurality of performance data, the performance data including time information, which method is characterized by comprising a step of changing the time information of the plurality of performance data in the main information in accordance with a value of the additional information and with a predetermined encoding algorithm. With this inventive method, the electronic watermark of the additional information is embedded in the form of a combination of changes of the time information in the plurality of performance data.
The present invention also provides an improved method of decoding additional information embedded, as an electronic watermark, in main information in accordance with the aforementioned second aspect, which method is characterized by comprising: a step of acquiring decoding key information corresponding to the encoding algorithm; and a step of inversely executing the encoding algorithm on the basis of the decoding key information acquired by the step of acquiring, to thereby decode the additional information hidden in the main information.
According to the second aspect of the present invention, the time information of the plurality of performance data in the main information is changed in accordance with a value of the additional information, and the electronic watermark of the additional information is embedded in the form of a combination of changes (changed states) in the time information of the plurality of performance data. Because the additional information is encoded in very complicated form, the thus-encoded additional information is very insusceptible to alteration by a dishonest user. It is desirable that the time information change be made with respect to such information a time information change of which does not adversely influence a reproductive performance based on the performance data. For example, the time information of plural kinds of tone generator setting information (or tone control information) may be changed. Changing the time information of the tone generator setting information is advantageous in that a not-so-great change in the time information of the tone generator setting information does not substantially influence a reproductive music performance, unlike time information of tone generation instructions (note-on events) and the like. Further, since the time information of the tone generator setting information is not changed very often, it is very unlikely that the additional information is altered unintentionally or unconsciously. Rather than by the above-mentioned time information change, the electronic watermark of the additional information may be embedded by changing duration times, from note-on timing to note-off timing, of a combination of plural tones in accordance with a value of the additional information. Such a duration time change may be made by altering the note-off timing rather than the note-on timing. Not-so-great change of the note-off timing, i.e., duration time, does not have a significant adverse influence on the reproductive music performance.
According to a third aspect of the present invention, there is provided a method of embedding additional information, as an electronic watermark, in main information including music performance data, the music performance data including status information indicative of respective statuses of individual ones of the performance data, which method is characterized by comprising a step of making control as to whether a particular one of the statuses should be used or not, the particular status being a status use/non-use of which has no significant influence on execution of a music performance. With this inventive method, an electronic watermark corresponding to the use/non-use of the particular status is embedded in the main information. Among examples of the particular status, use/non-use of which has no significant influence on execution of a music performance, is a MIDI running status. The MIDI running status indicates a situation where the current status of a given event in a performance sequence is the same as the immediately-preceding status, by omitting status information corresponding to the current status. Thus, where particular status information is omitted, it is indicated that the running status is being used, while where no status information is omitted in a region where a running status is usable, it is indicated that the running status is not being used. Because the use/non-use of the running status does not affect execution of the music performance, e.g., a one-bit electronic watermark can be embedded in the main information without the music performance being adversely influenced by whether the running status is being used or not. Such a feature can effectively diversify the form of the electronic watermark information embedding, and this diversification in the form of the electronic watermark information embedding is very useful in providing for a complicated encoding process with contents very hard to read or see through.
According to a fourth aspect of the present invention, there is provided a method of embedding additional information, as an electronic watermark, in main information including music performance data, the main information including non-performance data in addition to the music performance data, the non-performance data including text data, which method is characterized by comprising a step of controlling the number of spaces in the text data included in the non-performance data. With this inventive method, the electronic watermark of a value corresponding to the number of spaces is embedded in the main information. The xe2x80x9cnon-performance dataxe2x80x9d are, for example, MIDI meta event data. For instance, a total number of spaces in text data included in one meta event may be set in accordance with a desired value of the additional information. In an alternative, a total number of spaces between adjoining words in text data included in one meta event is set in accordance with a desired value of the additional information. In this way, an electronic watermark of a certain number of bits can be embedded in the main information. Because an increase/decrease in the number of spaces in the text data of the non-performance data does not affect a music performance, an electronic watermark of an appropriate number of bits can be embedded without the music performance being adversely influenced by embedding of the electronic watermark. Such a feature too can effectively diversify the form of the electronic watermark information embedding, and this diversification in the form of the electronic watermark information embedding is very useful in providing for a complicated encoding process with contents very hard to read or see through.
According to a fifth aspect of the present invention, there is provided an electronic information processing method of embedding additional information, as an electronic watermark, in main information including music performance data, which method is characterized by comprising a step of adding dummy data to the main information in accordance with a predetermined encoding algorithm. With this inventive method, an electronic watermark corresponding to the dummy data added to the main information is embedded in the main information. As an example, dummy data may be added right after given performance control data or non-performance data by duplicating or repeating the same performance control data or non-performance data. For example, even where two or more identical performance control data, instructing that a given effect should be changed to another effect, are arranged in succession, this redundant arrangement of the identical control data does not adversely influence a music performance, because the effect is changed only once in response to the first occurrence of the performance control data and the changed effect is maintained in the next occurrence of the performance control data. Therefore, such performance control data can be used appropriately as the dummy data. Even when identical non-performance data, such as meta events, are arranged in succession, a same meta event process is performed for each of the non-performance data, and the redundant placement of the identical non-performance data does not adversely influence the music performance. Thus, in this case too, one-bit electronic watermark information can be embedded depending on the presence/absence of the dummy data without the music performance being adversely influenced by the embedding. Further, by setting time information indicative of a time position of the dummy data in accordance with desired additional information, it is possible to embed the additional information of a value corresponding to the time information. As another example, a desired one of a plurality of tone generator channels may be set as a dummy channel that is not used for tone generation purposes, and the electronic watermark of a value corresponding to the thus-set dummy channel may be embedded in the main information. In this case too, the form of the electronic watermark information embedding can be highly diversified, which is very useful for constructing a complicated encoding process with contents very hard to read or see through.
According to a sixth aspect of the present invention, there is provided an electronic information processing method of embedding additional information, as an electronic watermark, in main information including music performance data, which method is characterized by comprising a step of selectively changing values of a predetermined kind of data among the music performance data in such a manner that a statistical distribution of the predetermined kind of data presents a pattern changed in accordance with a value of additional information to be embedded. With this inventive method, the additional information is embedded as the electronic watermark with the statistical distribution of the predetermined kind of data presenting the changed pattern. Because this electronic information processing method is designed to change a statistical distribution pattern of predetermined performance data, it can effectively aid in preventing an unauthorized user from tampering with or altering the information and can also appropriately deal with unintentional alteration, by an authorized user, of the additional information, because there is only a low possibility of the statistical distribution pattern greatly changing even when part of the performance data is tampered with or altered through editing whether intentionally or unintentionally. Further, this method too can significantly diversify the form of embedding of the electronic watermark information, which is very useful for building a complicated encoding process with contents very hard to read or see through.
According to a seventh aspect of the present invention, there is provided an electronic information processing method of embedding additional information, as an electronic watermark, in main information, which method is characterized by comprising a step of embedding a plurality of pieces of electronic watermark information in relation to a single item of additional information. Thus, an electronic watermark of a single item of additional information is embedded in the form of a plurality of pieces of electronic watermark information related to each other. This method too can even further enhance the effect of the electronic watermark and therefore is very useful for building a complicated encoding process with contents very hard to read or see through. Also, it is possible to increase the number of bits in each item of additional information that can be imparted to the main information, thereby increasing a total information amount in the impartable additional information.
As an example, one of the pieces of electronic watermark information may be embedded per divided additional information portion that is obtained by dividing, into a plurality of portions, the single item of additional information to be embedded. In this case, the additional information is reproduced by decoding the plural pieces of electronic watermark information from the main information and then combining the divided additional information portions corresponding to the decoded electronic watermark information.
As another example, at least a part of the additional information may be embedded as first electronic watermark information in the main information in accordance with a predetermined first encoding algorithm, while decoding key information, corresponding to the first encoding algorithm, is embedded as second electronic watermark information in the main information. In this case, the additional information is reproduced by decoding the second electronic watermark information from the main information and then decoding the first electronic watermark information from the main information using the second electronic watermark information as the decoding key information.
The present invention may be implemented not only as the method invention as set forth above but also as a system or apparatus invention. The present invention may also be practiced as a computer-readable storage medium storing a program for carrying out the inventive method. Also, the present invention may be practiced as a computer-readable storage medium containing data having electronic watermarks embedded therein.